1. Field of the Invention
The present invention relates to a magnetic recording medium manufacturing method that can restrain processing variations and decreases in etching rate at the time of etching.
2. Description of the Related Art
In recent years, BPM (Bit Patterned Media), DTM (Discrete Track Media), and the like have been used as perpendicular magnetic recording media. In each of those media, a concave-convex pattern or grooves are formed in a magnetic film, and the concave portions or the grooves are filled with a nonmagnetic material, to prevent magnetic interference between adjacent cells. A method of manufacturing such magnetic recording media is disclosed in Japanese Patent Application Laid-Open No. 2005-50468.
To process a magnetic film into a concave-convex pattern, a mask or a resist processed into a concave-convex pattern needs to be formed on the magnetic film, and the pattern needs to be transferred to the magnetic film by etching. The resist or mask is designed to increase the selectivity with respect to the adjacent layers and maintain the shape of the pattern. By maintaining the shape of the pattern, the magnetic film is processed to have concavities and convexities with predetermined depths and widths, and a higher magnetic recording density can be achieved.
To form concavities and convexities, the portions of the film located at the bottoms of grooves need to be etched by the amount equivalent to a predetermined film thickness. In that case, however, the etching amount varies depending on the film adhering state at portions (such as a substrate holder) surrounding the substrate, in addition to the discharge conditions.
To counter this problem, Japanese Patent Application Laid-Open No. 2001-156158 discloses a technique of removing the film adhering to a substrate holder by performing sputter etching on the substrate holder that is not holding a substrate.
By the sputter etching disclosed in Japanese Patent Application Laid-Open No. 2001-156158, various films adhering to the substrate holder can be removed. However, the etched films re-adhere to the substrate holder, and cannot be completely removed.